Core biopsy is a routine procedure used to obtain a sample of a biological tissue from a live organ for a laboratory examination. FIGS. 1A-1D depict schematically a core biopsy needle 10 used for taking core biopsy samples. Core biopsy needle 10 comprises a mandrel 12 and a Cannula 14. Mandrel 12 is an elongated solid needle having a distal tip 16 at the end of needle 10 and a notch 18 adjacent to distal tip 16. Notch 18 is an interior shaft recess, used for receiving the tissue sample. Cannula 14 is a sleeve exterior to mandrel 12 and is configured for sliding over mandrel 12.
During a core biopsy procedure distal tip 16 of core biopsy needle 10 is brought up to a few millimeters from a region to be sampled in an organ (FIG. 1A). Mandrel 12 is advanced forward into the organ, typically at a high speed to reduce pain in an awakened patient, allowing organ tissue to fill in notch 18 (FIG. 1B). Cannula 14 is then advanced forward over the mandrel, thereby cutting off a sample tissue which is left in notch 18 (FIG. 1C). Core biopsy needle 10 is removed from the organ and Cannula 14 is pulled back in order to expose and remove the sample tissue from notch 18 (FIG. 1D). The sample tissue is typically removed from notch 18 into a vial filled with a preservative solution such as a solution including formaldehyde, usually by hand using a syringe or using a small sharp-end tool. Several sample tissues may be put in a single vial during such a core biopsy procedure, being left in the preservative solution until taken through a preparation process for laboratory examination.
A typical preparation process prior to examination is detailed for example in U.S. Pat. No. 7,156,814, and may include the following steps:
a. A sample is manually taken out of the preservative solution using an appropriate tool, and placed in a sample box. Inside the sample box the sample is gently pressed, using a box cover, between two sheets of a soft material such as a sponge, which prevents displacement of the sample tissue inside the box. An example of a sample box is Tissue-Tek®Uni-Cassettes® by SAKURA FINETEK USA, INC. The sample box is then marked with a string (e.g. digits and letters) identifying the sample and its origin.
b. The tissue inside the box is taken through a chemical process of several hours, involving immersion in neutral buffered formaldehyde preservative solution, in ethanol, in xylene and in paraffin. Then the sample tissue is dried.
c. Dried tissue is removed from the sample box and placed in a metal mold, about the size of the sample box. The sample tissue is fixed to the base of the mold, typically using a drop of paraffin and by gently pressing onto the sample tissue. An example of a metal mold is Tissue-Tek® Base Molds by SAKURA FINETEK USA, INC.
d. The sample box, without cover, is fixed on top of the metal mold, and the space within, that is to say between the metal mold and the sample box, is filled with paraffin.
e. After the paraffin solidifies the metal mold is removed, leaving the sample box (with the marked string identifying the sample tissue) filled with a block of paraffin and with the sample tissue on top.
f. The sample box with the sample tissue is taken for slicing. Slices of typical thickness of a few microns are taken from the top surface of the paraffin block, carrying slices of the sample tissue therein.
g. A selected slice is placed between two glass plates and inserted to an oven for melting the paraffin. After removing the liquid paraffin, the sample tissue between two glass plates is taken for examination, e.g. under a microscope.